Hi: I am looking to add aftermarket speakers, an amp, and possibly a sub to my 2000 Audi A6. I want to keep the stock HU (Symphony). I do not have a Bose setup in the car. I was wondering how hard it would be to add these components. Basically, what do I need to do to the HU to enable me to install the rest of the stuff? Is this something I could do by myself or is it better to get it professionally done. I used to be heavy into car audio but I've been out of the game for about 6 years... Also, do you think it is worth it? Or should I just bite the bullet and get a new HU. Any response would be greatly appreciated!